Memory systems store data to be used by computers or other electronic devices. Various different memory systems may be used and accessed by computers or other electronic devices. For example, computers may use and access main memory as well as secondary storage such as, for example, hard disks and/or removable storage.
Main memory is memory that is accessible to a central processing unit (CPU) of a computer or electronic device. Main memory is used to store data that is deemed likely to be actively used by the CPU. The CPU may access data within the main memory that is identified by using virtual addresses to map to corresponding physical addresses associated with the main memory. Main memory generally is volatile. Therefore, data stored in main memory generally is lost when the device is powered down.
Secondary storage generally is memory that is not directly accessible by a CPU of a computer or electronic device. Because secondary storage generally is not directly accessible by the CPU, the CPU may use input/output (I/O) channels to access secondary storage. In addition, the CPU may use intermediate areas in primary storage to effect data transfers between the CPU and secondary storage. Secondary storage generally is non-volatile. Therefore, data stored in secondary memory generally is not lost when the device is powered down.